300's with short skirts

[Trigger]

I thought the short skirt bit would get attention 
I must of built over 120 CB750K engines in my time but, never have I come across this before. The one on the right is correct and both marked Honda 300.

[hairygit]

The shorter one looks as if it doesn't have the split skirt that the taller one has. Has somebody machined it down? The last time I saw something like that was a mate many years ago who made a home made big bore kit for his 550, using 750 pistons, and took some off the crown and the skirt by hand with a belt linisher. None of them matched heightwise, but he ran it hard for just over 3 years, until he holed 2 of the pistons. When he took it apart afterwards, the ones that holed had a crown thickness of just over 2mm, amazing it Lasted that long!

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[Bryanj]

Used to have a man in a van come round the shop every  two weeks(lethbridge and dark seems to come to mind) and in the back was a treasure trove of engine bits bought in from the east, lots of it marked Art or Honda but as to actual manufacture who knows, the FS1E barrels in "Genuine" boxes definitely were not but ran fin, apparently the Taiwanese at the time gave no never mind to patent or manufacture and would print whatever you asked for on the box. perhaps the pistons were from a source similar? or maybe lightened by someone?

[K2-K6]

Have you weighed them to see if they are different or matched to the familiar type?